Nonmetal-to-metal transition in Mg films on the Mo(1 1 2) surface

It has been observed in photoemission that increasing density of the adsorbed alkaline earth layers results in dramatic changes in the surface electronic structure. These changes are generally attributed to the nonmetal-to-metal transition in the films, which implies that at low coverages, the films can demonstrate quasi-dielectric behavior, while at near complete monolayer coverages, the overlayer attains metallic character. Presented are the results of self-consistent calculations (performed with the linearized augmented plane wave method for thin films) of the electronic structure of Mg layers, adsorbed on the Mo(1 1 2) surface, for two characteristic coverages: θ=0.5, when the alkaline earth films are believed to be dielectric, and θ=1, when the films are metallic. The nonmetal-to-metal transition in Mg films is evident from changes in the dispersion of the calculated surface resonance bands, in good agreement with recent experiments. These results are compared with related calculations of free Mg monolayers, and the role of main approximations to the realistic models of adsorption systems is discussed as well.